In this specification where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date publicly available, known to the public, part of the common general knowledge or known to be relevant to an attempt to solve any problem with which this specification is concerned.
It is a common and well-established practice to supplement crops with the major elements of plant nutrition C, H, O, N, P, K and S (also referred to as macronutrients). These major elements are available in many different forms, are used in almost every crop type and are commonly used in large quantities. The major elements are most commonly applied as solid forms (eg. granules, crystalline, pellets) to the soil prior to planting but there are liquid or soluble forms available which may be sprayed as a water solution. When applying solutions of these major elements foliarly to a crop, they may be used in conjunction with additives, such as wetting agents and oils, to enhance the efficacy of their application to a crop. For example, WO2008127661 describes the preparation of liquid fertiliser formulations of N, P, K and S containing oil using surfactants to combine the ingredients.
It has become a more common farming practice to apply certain essential elements (also referred to as micronutrients) directly to a crop during growth to counter a deficiency in the soil and/or to promote beneficial effects such as fortifying the produce. Crops are monitored and when a deficiency is evident, then particular foliar nutrient(s) can be applied to quickly correct it. Such foliar nutrients are nearly always applied by spraying an aqueous solution of the nutrient directly to the crop. This is an efficient method of managing nutrients as foliar nutrients tend to be taken up more quickly after application compared with pre-plant soil nutrition which generally requires the application of a large excess of the nutrients to be available in the soil for long periods. These essential elements are generally required in a much smaller quantity than the major elements (macronutrients above) and are typically much more expensive per unit. They may also have discreet functions within particular crops and hence may only be required at certain stages of the crop cycle. So the use of foliar sprays of micronutrients, as and when required is becoming more common practice.
Additives, such as wetting agents, may be included in the foliar nutrient product formulation or added separately to the spray tank to enhance the efficacy of their application to a crop.
Oil-based additives are commonly used with many agrichemicals (also known as agrochemicals) including herbicides, insecticides, defoliants, fungicides and growth regulators as well as with some macronutrients (see prior art example above). The function of oil-based additives when used with agrichemicals is mostly to assist in foliar penetration of the agrichemical where a solution of the agrichemical in the oil penetrates the waxy surface of the foliage. As a result, oil soluble agrichemicals generally benefit the most from the addition of oil-based additives. Such oil-based additives may be formulated with the agrichemical or added to the tank mix as a separate product. Oil-based additives are rarely, if ever, used with foliar nutrient products as the essential elements are generally available in a water soluble form and thus would not be expected to be soluble in lipophilic materials. Consequently, combinations of oils with essential elements applied foliarly is not expected to provide any significant benefit.